This invention relates to a machine for wrapping bundles of roll products, in particular, but without limiting the scope of the invention, roll products for household and/or bathroom use.
In the packaging industry, for certain consumer products such as rolls of paper for bathroom or household use, it is common practice to make multiple packages or bundles of products, where a sheet of plastic is wrapped around and holds together as one a certain predetermined number, or configuration, of products.
Within the bundle or configuration, the products are assembled in the form of vertical piles formed from horizontal layers neatly superposed and each in turn formed from a predetermined number of rolls placed side by side.
The formation of the bundles or the making up of the configuration is performed by special wrapping machines which basically comprise a bundle forming line where a plastic sheet is wrapped, folded and closed around the products; and a feed line which supplies the forming line with rolls which have been grouped together in suitable fashion.
The bundle forming line extends horizontally and comprises a power-driven chain conveyor.
The chain conveyor substantially comprises an endless flexible element or belt trained around a pair of pulleys to form an elongated, power-driven ring. The ring mounts a set of pusher rods distributed at regular intervals round the boundary of the ring and projecting transversally from the ring.
The feed line, on the other hand, extends vertically and lies under the forming line in the vicinity of one end of the forming line.
The feed line comprises a tube-like body with vertical walls and an elevator equipped with a horizontal platform that moves parallel to itself in a straight line inside, and between the top and bottom ends of, the tubular body.
The roll products are fed into the tubular body when the elevator platform is in the lowered position. Laterally confined by the walls of the tubular body and supported by the surface of the platform, the products are then made to move upwards in a straight line and gradually emerge from the tubular body intercepting as they do so a sheet of packaging material placed transversally along their path over the top of the tubular body.
When the products emerge from the tubular body, covered by the sheet of packaging material, they move under the continued lateral containing action applied to them previously until they reach a space located over the top of the tubular body and delimited by a pair of consecutive pusher rods which have in the meantime moved into line with the walls of the tubular body.
Once the bottom of the packaging sheet has been closed at the bottom of the product bundle, the conveyor ring slides lengthways along its boundary in such a way that the products are pushed off the elevator platform onto the forming line. Wrapping is then completed as the bundle advances along the forming line.
According to the current state of the art, the position of the chain conveyor relative to the elevator, or relative to the elevator platform, when the latter is at its topmost position, is fixed and is predetermined in such a way that the height of the space between consecutive pairs of pushers is such that the space can accommodate a maximum of two layers of superposed products.
In other terms, the wrapping machine can process groups of products arranged in a single layer or in two superposed layers.
The extension of the space lengthways along the forming line, on the other hand, can be adjusted by varying the pusher spacing according to the configuration required.
This can be done either manually by removing the pushers and refitting them in different positions or automatically by special adjustment mechanisms.
Whatever the case, the above mentioned machines permit the formation of single- or double-layer bundles whose configurations can be varied in the lengthwise direction along the forming line.
Wrapping machines of the kind described above therefore have the disadvantage of being limited to producing single- or double-layer packages whose configurations can be varied only in the lengthwise direction along the forming line.